You would do trial layouts on the floor and pick the one that you like. Grouping the same tiles together might be the way to go. Do a border around the edge of one type. Do a grouping in the middle of another tile. Fill in, in between with the third type.
The problem with this is that you bought random quantities and will have to deal with both the room layout and a random assortment of tiles.
Post a picture of these tiles.
You do realize that tiles that big require a more rigid floor and some special floor prep? And if these tiles are actually stone versus ceramic you might not even be able to use it with your structure.
Why don't you come back with the details of the structure and your plan for getting the tile down before you start.
Ron